An electrified vehicle (EV) utilizes a high voltage traction battery or other type of energy storage device (ESD) to provide propulsion energy for an electric drive system. When the energy level is reduced or depleted, the battery can be charged by coupling the EV to a residential electric grid or to a public or commercial charging station. Fully charged, the battery can store energy for future driving operations. In the recent past, it has been suggested that the energy stored at an EV battery can be used for operations other than driving the vehicle. For example, it has been proposed that the battery of an electric vehicle be used to provide energy back to a residential electric grid. A vehicle-to-home (V2H) energy transfer process can reduce home utility costs as energy can be stored in a vehicle battery during low-demand, low energy cost time periods, then accessed during time periods in which energy costs are higher. In addition, as a home electric grid is connected to a municipal utility grid, energy transferred to the home grid can also be used supplement a utility electric grid during peak demand times. U.S. Patent Publication No. 2011/0204720 to Ruiz et al. explains how such a system could be configured. However, the Ruiz system requires an extensive and complex network of control and monitoring modules in addition to the electrical circuitry and equipment necessary to conduct the actual energy transfers between the vehicle, home grid and utility grid.
Describing a less ambitious system, U.S Patent Application Publication 2011/0309674 to Kamachi discloses a power control system that can be used to supply power to a residence during a power outage. While narrower in scope than the Ruiz system, and thus somewhat less complex, the Kamachi system relies on a power converter installed at a building that is coupled to first and second batteries at an electric vehicle. The first battery, the vehicle traction or driving battery, is used to provide energy that the power converter can transfer to the home electric grid, and the second battery, the vehicle auxiliary battery, used for vehicle auxiliary equipment such as lights, air conditioner, etc., is used to power operation of the power converter itself. An equipment controller installed at the house can control the energy converted at the power converter.
While adequate for their intended purposes, the proposals described above, as well as other prior art directed to V2H applications, suffer several shortcomings. For example, both require additional equipment to be installed at a residence, the installation and servicing of which may be beyond the price point considered affordable by many consumers. In addition, many such systems, like the Kamachi system described above, include an equipment controller installed at the building. This feature can impose limitations on the manner in which energy can be transferred, such as a limitation that stored energy can be transferred from a vehicle battery only when the vehicle is tethered to a residential or commercial/industrial building. When the appliances or electrical equipment to be powered reside at the building, this limitation may prove insignificant. For example, if a vehicle battery is being used to provide power to a refrigerator, stove or other appliance at the building during a power outage, reliance on a controller at the building, and connection of the vehicle to the building, do not pose any problem. However, this type of system cannot be used in a situation in which an operator would like to use a vehicle's battery to power equipment that is not within the building, or is not connected to the home's electric grid. For example, a user on a camping trip may desire to use a vehicle's battery energy to power equipment such as a heater, microwave oven, air conditioner, etc. at a remote campsite. Alternatively, a construction worker may need power for operating high current electric tools and power equipment such as drills, saws, air compressors and the like at a worksite. In either case, since there is no building grid to tap into, the proposed systems cannot address the immediate need.